For the past five years, Ephonia Green has publicized her donations of wedding gowns to military brides, describing in interviews how she was moved to repay their service with her own goodwill by giving away 275 ensembles from her Upper Marlboro shop.

Federal court records suggest how she may have been able to afford that: Since 2005, while working as a $56,000-a-year administrative assistant, Green allegedly stole $5.1 million from the Association of American Medical Colleges.

The District-based nonprofit organization represents accredited medical schools and major teaching hospitals and administers the admissions test known as the MCAT.

In a case thought to be one of the largest embezzlements from an area nonprofit group, Green is scheduled to appear Monday at a plea hearing in U.S. District Court in Washington.

The charges against Green, 44, are contained in an eight-page “criminal information,” which can be filed in a felony case only with a defendant’s cooperation and signals that a plea agreement is near.

Of the alleged loss, nearly $1.4 million was paid via 74 checks made out to Green’s bridal business, known as Couture Miss Bridal & Formal, court files show.

Green’s attorney, William Brennan, declined to comment.

The court document contends that Green enriched herself by registering company trade names and opening bank accounts in business names that closely resembled those of legitimate vendors to the association.

At the association, Green had enough access to key financial systems that she was able to create fake invoices in the names of legitimate groups that she then approved for payment, the court files contend. And when the checks were ready, she had them returned to her, not sent to the vendors, prosecutors charge.

Under that system, a spelling change of just four letters allegedly netted $3.7 million for Green when she purportedly created nearly 200 false invoices in the name of the well-known Brookings Institution policy center but deposited the checks into accounts she opened for her own “Brookings Institute.”

Last month, a Washington Post investigation revealed more than 1,000 “significant diversions” of assets at nonprofit organizations discovered during a Post analysis of federal disclosure records filed by groups across the country. Many of the diversions identified by The Post were described as acts of theft and fraud carried out by insiders, contractors and investment advisers.

Federal prosecutors filed charges swiftly in the alleged association theft, a break from some past embezzlements from nonprofit groups. Youth Service America, a national charity also based in the District, alerted authorities in 2009 that a former employee had stolen $2 million. But charges were not filed in that case until almost four years later, after The Post questioned prosecutors about the incident as part of its broad examination of theft from charities. The former employee pleaded guilty.

The alleged years-long plot by Green unraveled in July when a bank withheld payment on a $113,000 check that Green was depositing — into an account she had set up two days earlier — and notified the medical colleges association, court records indicate.

The amount matched a quarterly payment due to one of the association’s legitimate vendors — but the invoice number did not align with numbers the outside group used on its bills, said Frank Trinity, the association’s chief legal officer.

Darrell G. Kirch, president of the association, said the group is experiencing “betrayal and profound disappointment” and that “the people who are closest to it have felt devastated.”

Green started at the association in 1998 and worked in support positions where she chiefly handled the details of arranging large meetings for the group, Trinity said.

After the tip-off from the bank, the association grew suspicious of more payments, Trinity said, before firing Green in July, calling federal authorities, alerting its board and hiring an outside attorney and forensic accountants.

The internal investigation, Trinity said, suggested that Green began her alleged scheme modestly by submitting small, bogus bills to cover the registration fees of staff members supposedly headed to conferences.

The alleged embezzlement ballooned starting in 2005, the criminal court files charge, until Green netted an amount that would be close to 90 times her salary.

The criminal filing does not explain where all of the money went. The filing contends that some was used to cover an auto loan, some went to church donations and some paid for personal items.

Other money helped pay expenses of the bridal shop that Green owned, court files state. Couture Miss brought Green attention as a “fairy godmother” to military brides, as some news accounts described her.

On Saturday, the shop was open and busy. There were dresses in the display window and customers flipped through selections on tightly packed clothing carousels.

Trinity said the association was unaware of Green’s television appearances touting her giveaways and learned of her business only after “doing some Googling” following the bank call about a questionable check.

“I think they put a high priority on this case,” Trinity said of federal prosecutors.

In a separate civil case, the association is asking a federal court to prevent Green and her husband from disposing of property including what the association said is their $1.1 million home in Upper Marlboro.

The association has a $3 million insurance claim pending to try to recover some of its money, Trinity said.

The group has tightened its accounting, auditing and vendor registrations, said Kirch, while acknowledging that “nonprofits have lacked some of the rigor that is enforced in for-profit organizations on monitoring finances.”

Ann E. Marimow and Jennifer Jenkins contributed to this report.

Mary Pat FlahertyMary Pat Flaherty works on investigative and long-range stories. Her work has won numerous national awards, including the Pulitzer Prize. Follow

Joe StephensJoe Stephens joined The Washington Post in 1999 and specializes in in-depth enterprise reporting.